Livermore car buff Cody Brown loved drifting — an adrenaline-filled motor sport in which a driver intentionally oversteers and loses wheel traction but maintains control of the car. Ironically, the 20-year-old was killed last month in a freak highway accident that remains a mystery.

It took place Oct. 27 about 7:43 p.m. as Brown and his mother, 47-year-old Gina Brown-Robison, were on their way home from Las Vegas, where they had been visiting Brown”s elderly grandparents. Brown was at the wheel, following a truck traveling north on Interstate 5 near Crows Landing, south of Patterson.

Approaching them and driving southbound was a tractor trailer. Near Fink Road, it”s believed one of the southbound truck”s axles failed, causing a rim and tire assembly from the trailer to break off at the axle hub and begin bounding across the center median into the northbound lane.

According to the California Highway Patrol, the rim and tire first hit the left side of the truck driving in front of Brown and glanced off, striking the windshield of the car carrying Brown and his mother. Brown was killed instantly; Gina Brown-Robison, who according to family was resting in a reclined position in the car, suffered minor injuries. The car hit the guardrail and careened over traffic lanes, coming to rest partially down an embankment.

The truck with the missing wheel continued on and despite CHP efforts to locate it and the driver has not been found. Inquiries at truck stations and scales have not turned up any answers, said CHP Officer Brandon Moore. The truck driver may not even know a collision occurred.

“Unfortunately, there are a lot of unknowns, which we don”t like,” he said. “I”ve heard of things like it, but I”ve been in this office about 13 years, and this is the first time I can remember something like this.”

The family had counted on life insurance to cover Brown”s burial costs, but the payment — and the burial itself — has been delayed while issues over coverage are debated, said Brown”s stepfather, Rod Robison, of Livermore.

To help, friends have established a donation website at the crowdfunding site gofundme. Among the donors so far are members of the car club Brown helped found, called Twisted Drift.

“We started out small, just (Brown) and my brother,” recalled Eric Frydendal, of Livermore. “He actually introduced everyone in the group … Cody was always good for a laugh, always the person who had everybody”s back and could cheer up anybody in a second.””

Donations would be a welcome gift to a family whose resources have been stretched thin due to Gina Brown-Robison”s multiple medical issues, which include three heart attacks. Cody Brown, a Del Valle High School graduate,worked to contribute to the family income until he was put on disability after a car accident and an injury at work.

TO HELPAnyone with information on the truck that lost its rim and tire, or the identity of the driver, is asked to call the California Highway Patrol”s Modesto Area office at 209-545-7440.Donations to help with burial expenses for Cody Brown may be made at www.gofundme.com/gixdw8.